How severe is CVE-2023-26491?

CVE-2023-26491 has a CVSS score of 5.4/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2023-26491?

CVE-2023-26491 affects the following packages: rsshub (npm). Ecosystems affected: npm.

How do I fix CVE-2023-26491?

Update rsshub to 1.0.0-master.c910c4d or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-26491 is resolved across your whole dependency graph.

How do I detect CVE-2023-26491 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rsshub. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2023-26491 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2023-26491?

O3 pinpoints whether CVE-2023-26491 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2023-26491 actively exploited in the wild?

No public exploit code has been indexed for CVE-2023-26491 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2023-26491?

CVE-2023-26491 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 35th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2023-26491?

CVE-2023-26491 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2023-26491 published, and has it been updated?

CVE-2023-26491 was published on March 3, 2023 and was last updated on April 2, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2023-26491: rsshub Cross-Site Scripting (Medium 5.4)

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk35th percentile-0.40%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.

rsshubnpm

11Kdownloads / week

Description

RSSHub is an open source and extensible RSS feed generator. When the URL parameters contain certain special characters, it returns an error page that does not properly handle XSS vulnerabilities, allowing for the execution of arbitrary JavaScript code. Users who access the deliberately constructed URL are affected. This vulnerability was fixed in version c910c4d28717fb860fbe064736641f379fab2c91. Please upgrade to this or a later version, there are no known workarounds.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`rsshub`	all versions	1.0.0-master.c910c4d

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rsshub. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update rsshub to 1.0.0-master.c910c4d or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-26491 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2023-26491 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2023-26491. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

RSSHub is an open source and extensible RSS feed generator. When the URL parameters contain certain special characters, it returns an error page that does not properly handle XSS vulnerabilities, allowing for the execution of arbitrary JavaScript code. Users who access the deliberately constructed URL are affected. This vulnerability was fixed in version c910c4d28717fb860fbe064736641f379fab2c91. Please upgrade to this or a later version, there are no known workarounds.

O3 Security · Impact-Aware SCA

Is CVE-2023-26491 in your dependencies?

O3 detects CVE-2023-26491 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works

CVE-2023-26491